Founded by Methodists and Quakers in the present-day town of Trinity in 1838, the school moved to Durham in 1892. In 1924, tobacco and electric power industrialist James B. Duke established The Duke Endowment, at which time the institution changed its name to honor his deceased father, Washington Duke.
The university has “historical, formal, on-going, and symbolic ties” with the United Methodist Church, but is a nonsectarian and independent institution. Duke’s research expenditures in the 2010 fiscal year topped $983 million, the fifth largest figure in the nation. Competing in the Atlantic Coast Conference, Duke’s athletic teams—known as the Blue Devils—have captured 13 team national championships, including four by its high profile men’s basketball team.
The university’s campus spans over 8,600 acres (35 km2) on three contiguous campuses in Durham as well as a marine lab in Beaufort. Duke’s main campus—designed largely by African American architect Julian Abele—incorporates Gothic architecture with the 210-foot (64 m) Duke Chapel at the campus’ center and highest point of elevation. The forest environs surrounding parts of the campus belie the University’s proximity to downtown Durham. Construction projects have updated both the freshmen-populated Georgian-style East Campus and the main Gothic-style West Campus, as well as the adjacent Medical Center over the past five years.
Duke University research articles from Innovation Toronto
- Study Points to Fast-Acting Drug for OCD – July 23, 2016
- Bouncing droplets remove contaminants and self-clean without being superhydrophobic – July 6, 2016
- Robotic motion planning in real-time – June 22, 2016
- Bioengineered Blood Vessel Appears Safe for Dialysis Patients and Becomes Human Tissue – May 16, 2016
- Uncovering Genetic Elements That Drive Limb and Tissue Regeneration – April 7, 2016
- New class of molecular ‘lightbulbs’ illuminate MRI bioimaging in real time – March 27, 2016
- Rapidly Building Arteries that Produce Biochemical Signals – March 1, 2016
- Traveling Salesman Uncorks Synthetic Biology Bottleneck – January 6, 2016
- Using — And Sharing — New Technologies Is Key For Conservation – October 7, 2015
- Engineers Unlock Remarkable 3D Vision from Ordinary Digital Camera Technology – September 18, 2015
- Stem Cells Provide Lasting Pain Relief in Mice – July 15, 2015
- Finding New Life for First-Line Antibiotics – April 26, 2015
- Crowdsourcing with Mobile Apps Brings ‘Big Data’ To Psychological Research – December 23, 2014
- Revving up fluorescence for superfast LEDs & quantum cryptography – October 19, 2014
- The Skin Cancer Selfie – October 8, 2014
- Extinctions during human era worse than thought – September 6, 2014
- Water ‘Thermostat’ Could Help Engineer Drought-Resistant Crops – August 31, 2014
- World Cup to Debut Mind-Controlled Robotic Suit – June 10, 2014
- The Duke University breakthrough that could keep your cancer in remission forever – May 18, 2014
- Neural Networks Imitate Intelligence of Biological Brains – May 17, 2014
- Self-Healing Engineered Muscle Grown in the Laboratory
- Catheter Innovation Destroys Dangerous Biofilms
- ‘Superlens’ Extends Range of Wireless Power Transfer
- Supercomputers Join Search for ‘Cheapium’
- Surgeons at Duke University Hospital Implant Bioengineered Vein
- Duke University researchers create polymer coating to keep bacteria, barnacles at bay
- Duke Engineers Build Living Patch for Damaged Hearts
- Duke researchers engineer cartilage from pluripotent stem cells
- Copper Promises Cheaper, Sturdier Fuel Cells
- Wireless Device Converts “Lost” Energy into Electric Power
- Shifting employee bonuses from self to others increases satisfaction and productivity at work
- Scientists Demonstrate New Method for Harvesting Energy from Light
- Researcher controls colleague’s motions in 1st human brain-to-brain interface
- Far From Being Harmless, the Effects of Bullying Last Long Into Adulthood
- First-Ever Therapeutic Offers Hope for Improving Blood Transfusions
- Light and nanoprobes detect early signs of infection
- Genetic editing shows promise in Duchenne muscular dystrophy
- New Method for Producing Clean Hydrogen
- Do-It-Yourself Invisibility with 3-D Printing
- Medical Equipment Donated to Developing Nations Usually Ends Up on the Junk Heap
- Brain scans might predict future criminal behavior
- Brain-to-brain interface allows transmission of tactile and motor information between rats
- Scrap “unwinnable” drugs war and divert funds into curbing global antibiotic misuse
- Brain prostheses create a sense of touch
- Novel Materials Shake Ship Scum
- Slow-release jelly delivers drugs better
- Novel sensor provides bigger picture
- Scientists Develop Device for Image Compression
- Sprinkled Nanocubes Could Hold Light Tight for Efficient Solar Panels
- Hope on the Horizon for Asthma Sufferers
- Coming Soon: Artificial Limbs Controlled by Thoughts
- Megapixel Camera? Try Gigapixel
- Scar Tissue Turned Into Heart Muscle Without Using Stem Cells
- Large-Scale Analysis Finds Majority of Clinical Trials Don’t Provide Meaningful Evidence
- A New Crop of Digital Science Books Will Change the Way Students Learn
- Changing the Texture of Plastic Instantly
- Exotic Material Boosts Electromagnetism Safely
- Energy Harvesting: Wringing More Energy out of Everyday Motions
- With Prevalence of Nanomaterials Rising, Panel Urges Review of Risks
- Vaccines to Boost Immunity Where It Counts, Not Just Near Shot Site
- Jumping droplets could offer more efficient thermal management
- Digital Merit Badges For Job Hunters
- Monkeys’ brain waves offer paraplegics hope
- Harnessing the Power of Positive Thoughts and Emotions to Treat Depression
- Hybrid Solar System Makes Rooftop Hydrogen
- Manipulating Light at Will
- Restoring Happiness in People With Depression
- Automatic photo tagging with TagSense smartphone app
- New Wifi Tech Could Double Your Phone’s Battery Life
- Food Allergy Therapies Move Closer to Approval
- Metamaterials could significantly boost wireless power transmission
- Skin cancer-detecting laser tool developed
- New Antibacterial Chemical Compound Discovered
- Color-changing plants detect pollutants and explosives
- Shooting for the Moon: How Universities Can Turn Innovation into Companies
- Free the H-1Bs, Free the Economy
- Renewable Energies Will Benefit US Workers’ Health, Expert Predicts
- When the Software Is the Sportswriter
- Scientists Isolate a Gene That Boosts Plant Root Growth
- Researchers discover way to turn off severe allergic reaction to food in mice
- Next-gen robotic surgeons could eliminate need for doctors in simple surgeries
- Bye-Bye Batteries: Radio Waves as a Low-Power Source
- Energy-efficiency measures could save consumers $41 billion
- New visa proposal to help create the next big thing
- Harvesting Energy From Nature’s Motions
- Weary of Looking for Work, Some Create Their Own
- Next Generation Cloaking Device Demonstrated
- Telerobotic system designed to treat bladder cancer
- Robotic fish to patrol for pollution in harbours
- How Do We Measure What Really Counts In The Classroom
- In Study, Drug Delays Worsening of Breast Cancer, With Fewer Side Effects
- US-China Deal Intended to Speed Clean Coal Research
- Effortless Sailing With Fluid Flow Cloak
- EnerJ system could cut computer power consumption by up to 90 percent
- Bendable displays and solar cells using cheap copper nanowires
New technology shapes sound waves for applications from speakers to ultrasound imaging
Research Triangle engineers have developed a simple, energy-efficient way to create three-dimensional acoustic holograms. The technique could revolutionize applications ranging from home stereo systems to medical ultrasound devices.
Most everyone is familiar with the concept of visual holograms, which manipulate light to make it appear as though a 3-D object is sitting in empty space. These optical tricks work by shaping the electromagnetic field so that it mimics light bouncing off an actual object.
Sound also travels in waves. But rather than electromagnetic energy traveling through space, sound propagates as pressure waves that momentarily compress the molecules they are traveling through. And just like visible light, these waves can be manipulated into three-dimensional patterns.
A close up look at the metamaterial device that can create acoustic holograms. Each grid or block contains a spiral of one of 12 various densities, each of which slows sound waves by a specific amount.
“We show the exact same control over a sound wave as people have previously achieved with light waves,” said Steve Cummer, professor of electrical and computer engineering at Duke University. “It’s like an acoustic virtual reality display. It gives you a more realistic sense of the spatial pattern of the sound field.”
In a paper published Oct. 14 in Nature Scientific Reports, researchers at Duke and North Carolina State University show that they can create any three-dimensional pattern they want with sound waves. The achievement is made possible by metamaterials—synthetic materials composed of many individual, engineered cells that together produce unnatural properties.
A computer rendering if the 12 different kinds of spirals contained in the metamaterial blocks, each of which slows sound waves by a specific amount. Organizing the various spirals in an array can bend the shape of in incoming wave of sound.
In this case, the metamaterials resemble a wall of Legos. Each individual block is made of plastic by a 3-D printer and contains a spiral within. The tightness of the spiral affects the way sound travels through it—the tighter the coil, the slower sound waves travel through it.
While the individual blocks can’t influence the sound wave’s direction, the entire device effectively can. For example, if one side of the sound wave is slowed down but not the other, the resulting wave fronts will be redirected so that the sound is bent toward the slow side.
“Anybody can tell the difference between a single stereo speaker and a live string quartet playing music behind them,” explained Yangbo “Abel” Xie, a doctoral student in Cummer’s laboratory. “Part of the reason why is that the sound waves carry spatial information as well as notes and volume.”
By calculating how 12 different types of acoustic metamaterial building blocks will affect the sound wave, researchers can arrange them in a wall to form any wave pattern on the other side that they want. With enough care, the sound waves can produce a specific hologram at a specific distance away.
“It’s basically like putting a mask in front of a speaker,” said Cummer. “It makes it seem like the sound is coming from a more complicated source than it is.”
A computer rendering of a sound wave that traveled through an array of acoustic metamaterial and was shaped into a pattern like the letter A one foot past the array. This pattern could not be seen, only heard.
Cummer and Xie, in collaboration with Yun Jing, assistant professor of mechanical and aerospace engineering at NC State, and Tarry Shen, a doctoral student in Jing’s lab, proved their sound mask works in two different ways. In the first test, they assembled a metamaterial wall that manipulated an incoming sound wave into a shape like the letter “A” about a foot away. In a second demonstration, they showed that the technique can focus sound waves into several “hot spots”—or loud spots—of sound, also a foot from the device.
There are existing technologies that can also produce this effect. Modern ultrasound imaging devices, for example, use phased arrays with many individual transducers that can each produce precisely controlled sound waves. But this approach has its drawbacks.
“If you’ve ever had an ultrasound done, you know there’s a small wand attached to a much bigger machine a few feet away,” said Cummer. “Not only can this setup be cumbersome, it consumes an enormous amount of power. Our approach can help produce the same effect in a cheaper, smaller system.”
For the metamaterial device to work in such applications, however, each cell must be smaller than the waves it is manipulating. And for ultrasound technologies that operate in the megahertz range, this means the individual cells would have to be 100 times smaller than in the current demonstration blocks.
Computer simulations and experimental results of the effectiveness of the metamaterial acoustic hologram device producing the letter A. The sound wave was manipulated to create the letter A 300mm past the metamaterial device. Test results show a result close to calculations.
Cummer and Xie are looking for industry partners to show that this sort of fabrication would be possible. They are also shopping the idea around to industries that work in the kilohertz range, such as aerial sensing and imaging technologies. And of course, they’re speaking with sound companies to make a single speaker sound more like a live orchestra.
Computer simulations and experimental results of the effectiveness of the metamaterial acoustic hologram device producing several focal points or “hot spots.” The sound wave was manipulated to create the hot spots 300mm past the metamaterial device. Test results show a result close to calculations.
“We’re currently in the exploration phase, trying to determine where this technology would be useful,” said Xie. “Any scenario where your goal is to control sound, this idea could be deployed. And it could be deployed to make something totally new, or to make something that already exists better, simpler or cheaper.”
‘Love hormone’ gives greater sense of spirituality than a placebo
Oxytocin has been dubbed the “love hormone” for its role promoting social bonding, altruism and more. Now new research from Duke University suggests the hormone may also support spirituality.
In the study, men reported a greater sense of spirituality shortly after taking oxytocin and a week later. Participants who took oxytocin also experienced more positive emotions during meditation, said lead author Patty Van Cappellen, a social psychologist at Duke.
“Spirituality and meditation have each been linked to health and well-being in previous research,” Van Cappellen said. “We were interested in understanding biological factors that may enhance those spiritual experiences.
“Oxytocin appears to be part of the way our bodies support spiritual beliefs.”
Study participants were all male, and the findings apply only to men, said Van Cappellen, associate director of the Interdisciplinary and Behavioral Research Center at Duke’s Social Science Research Institute. In general, oxytocin operates somewhat differently in men and women, Van Cappellen added. Oxytocin’s effects on women’s spirituality still needs to be investigated.
The results appears online in the journal Social Cognitive and Affective Neuroscience.
Oxytocin occurs naturally in the body. Produced by the hypothalamus, it acts as a hormone and as a neurotransmitter, affecting many regions of the brain. It is stimulated during sex, childbirth and breastfeeding. Recent research has highlighted oxytocin’s possible role in promoting empathy, trust, social bonding and altruism.
To test how oxytocin might influence spirituality, researchers administered the hormone to one group and a placebo to another. Those who received oxytocin were more likely to say afterwards that spirituality was important in their lives and that life has meaning and purpose. This was true after taking into account whether the participant reported belonging to an organized religion or not.
Participants who received oxytocin were also more inclined to view themselves as interconnected with other people and living things, giving higher ratings to statements such as “All life is interconnected” and “There is a higher plane of consciousness or spirituality that binds all people.”
Study subjects also participated in a guided meditation. Those who received oxytocin reported experiencing more positive emotions during meditation, including awe, gratitude, hope, inspiration, interest, love and serenity.
Oxytocin did not affect all participants equally, though. Its effect on spirituality was stronger among people with a particular variant of the CD38 gene, a gene that regulates the release of oxytocin from hypothalamic neurons in the brain.
Van Cappellen cautioned that the findings should not be over-generalized. First of all, there are many definitions of spirituality, she noted.
“Spirituality is complex and affected by many factors,” Van Cappellen said. “However, oxytocin does seem to affect how we perceive the world and what we believe.”
Learn more: OXYTOCIN ENHANCES SPIRITUALITY, NEW STUDY SAYS
Duke engineers use CRISPR to generate neuronal cells from connective tissue
Researchers have used CRISPR—a revolutionary new genetic engineering technique—to convert cells isolated from mouse connective tissue directly into neuronal cells.
In 2006, Shinya Yamanaka, a professor at the Institute for Frontier Medical Sciences at Kyoto University at the time, discovered how to revert adult connective tissue cells, called fibroblasts, back into immature stem cells that could differentiate into any cell type. These so-called induced pluripotent stem cells won Yamanaka the Nobel Prize in medicine just six years later for their promise in research and medicine.
Since then, researchers have discovered other ways to convert cells between different types. This is mostly done by introducing many extra copies of “master switch” genes that produce proteins that turn on entire genetic networks responsible for producing a particular cell type.
Now, researchers at Duke University have developed a strategy that avoids the need for the extra gene copies. Instead, a modification of the CRISPR genetic engineering technique is used to directly turn on the natural copies already present in the genome.
These early results indicate that the newly converted neuronal cells show a more complete and persistent conversion than the method where new genes are permanently added to the genome. These cells could be used for modeling neurological disorders, discovering new therapeutics, developing personalized medicines and, perhaps in the future, implementing cell therapy.
The study was published on August 11, 2016, in the journal Cell Stem Cell.
“This technique has many applications for science and medicine. For example, we might have a general idea of how most people’s neurons will respond to a drug, but we don’t know how your particular neurons with your particular genetics will respond,” said Charles Gersbach, the Rooney Family Associate Professor of Biomedical Engineering and director for the Center for Biomolecular and Tissue Engineering at Duke. “Taking biopsies of your brain to test your neurons is not an option. But if we could take a skin cell from your arm, turn it into a neuron, and then treat it with various drug combinations, we could determine an optimal personalized therapy.”
“The challenge is efficiently generating neurons that are stable and have a genetic programming that looks like your real neurons,” says Joshua Black, the graduate student in Gersbach’s lab who led the work. “That has been a major obstacle in this area.”
In the 1950s, Professor Conrad Waddington, a British developmental biologist who laid the foundations for developmental biology, suggested that immature stem cells differentiating into specific types of adult cells can be thought of as rolling down the side of a ridged mountain into one of many valleys. With each path a cell takes down a particular slope, its options for its final destination become more limited.
If you want to change that destination, one option is to push the cell vertically back up the mountain—that’s the idea behind reprogramming cells to be induced pluripotent stem cells. Another option is to push it horizontally up and over a hill and directly into another valley.
“If you have the ability to specifically turn on all the neuron genes, maybe you don’t have to go back up the hill,” said Gersbach.
Previous methods have accomplished this by introducing viruses that inject extra copies of genes to produce a large number of proteins called master transcription factors. Unique to each cell type, these proteins bind to thousands of places in the genome, turning on that cell type’s particular gene network. This method, however, has some drawbacks.
“Rather than using a virus to permanently introduce new copies of existing genes, it would be desirable to provide a temporary signal that changes the cell type in a stable way,” said Black. “However, doing so in an efficient manner might require making very specific changes to the genetic program of the cell.”
In the new study, Black, Gersbach, and colleagues used CRISPR to precisely activate the three genes that naturally produce the master transcription factors that control the neuronal gene network, rather than having a virus introduce extra copies of those genes.
CRISPR is a modified version of a bacterial defense system that targets and slices apart the DNA of familiar invading viruses. In this case, however, the system has been tweaked so that no slicing is involved. Instead, the machinery that identifies specific stretches of DNA has been left intact, and it has been hitched to a gene activator.
The CRISPR system was administered to mouse fibroblasts in the laboratory. The tests showed that, once activated by CRISPR, the three neuronal master transcription factor genes robustly activated neuronal genes. This caused the fibroblasts to conduct electrical signals—a hallmark of neuronal cells. And even after the CRISPR activators went away, the cells retained their neuronal properties.
“When blasting cells with master transcription factors made by viruses, it’s possible to make cells that behave like neurons,” said Gersbach. “But if they truly have become autonomously functioning neurons, then they shouldn’t require the continuous presence of that external stimulus.”
The experiments showed that the new CRISPR technique produced neuronal cells with an epigenetic program at the target genes matching the neuronal markings naturally found in mouse brain tissue.
“The method that introduces extra genetic copies with the virus produces a lot of the transcription factors, but very little is being made from the native copies of these genes,” explained Black. “In contrast, the CRISPR approach isn’t making as many transcription factors overall, but they’re all being produced from the normal chromosomal position, which is a powerful difference since they are stably activated. We’re flipping the epigenetic switch to convert cell types rather than driving them to do so synthetically.”
The next steps, according to Black, are to extend the method to human cells, raise the efficiency of the technique and try to clear other epigenetic hurdles so that it could be applied to model particular diseases.
“In the future, you can imagine making neurons and implanting them in the brain to treat Parkinson’s disease or other neurodegenerative conditions,” said Gersbach. “But even if we don’t get that far, you can do a lot with these in the lab to help develop better therapies.”
Brain receptor acts as switch for OCD symptoms in mice
A single chemical receptor in the brain is responsible for a range of symptoms in mice that are reminiscent of obsessive-compulsive disorder (OCD), according to a Duke University study that appears online in the journal Biological Psychiatry.
The findings provide a new mechanistic understanding of OCD and other psychiatric disorders and suggest that they are highly amenable to treatment using a class of drugs that has already been investigated in clinical trials.
“These new findings are enormously hopeful for considering how to approach neurodevelopmental diseases and behavioral and thought disorders,” said the study’s senior investigator Nicole Calakos, M.D., Ph.D., an associate professor of neurology and neurobiology at the Duke University Medical Center.
OCD, which affects 3.3 million people in the United States, is an anxiety disorder that is characterized by intrusive, obsessive thoughts and repeated compulsive behaviors that collectively interfere with a person’s ability to function in daily life.
Researchers at Duke University and the University of British Columbia are exploring whether surfaces can shed dirt without being subjected to fragile coatings
Scalpels that never need washing. Airplane wings that de-ice themselves. Windshields that readily repel raindrops. While the appeal of a self-cleaning, hydrophobic surface may be apparent, the extremely fragile nature of the nanostructures that give rise to the water-shedding surfaces greatly limit the durability and use of such objects.
To remedy this, researchers at Duke University in Durham, North Carolina and the University of British Columbia in Vancouver, Canada, are investigating the mechanisms of self-propulsion that occur when two droplets come together, catapulting themselves and any potential contaminants off the surface of interest. They ultimately hope to determine whether superhydrophobicity — a surface that is impossible to wet — is a necessary requirement for self-cleaning surfaces.
“The self-propelled catapulting process is somewhat analogous to pogo jumping,” said Chuan-Hua Chen, an associate professor in the Department of Mechanical Engineering and Materials Science at Duke University. He and his colleagues present their work this week in Applied Physics Letters, from AIP Publishing.
When the droplets coalesce, or come together on a solid particle, they release energy – analogous to the release of biochemical energy of a human body on a pogo stick. The energy is then converted through the interaction between the oscillating liquid drop and the solid particle – analogous to the storage and conversion of energy by the spring mechanism of the pogo stick.
“In both cases, the catapulting is produced by internally generated energy, and the ultimate launching comes from the ground that supports the payload – the solid particle or the pogo stick,” Chen said.
Duke University engineers and computer scientists develop a new computer processor specially designed for robotic motion planning
Once they’ve mastered the skills of toddlerhood, humans are pretty good at what roboticists call “motion planning” — reaching around obstacles to precisely pick up a soda in a crowded fridge, or slipping their hands around a screen to connect an unseen cable.
But for robots with multi-jointed arms, motion planning is a hard problem that requires time-consuming computation. Simply picking an object up in an environment that has not been pre-engineered for the robot may require several seconds of computation.
Duke University researchers have introduced a specially-designed computer processor for motion planning that can plan up to 10,000 times faster than existing approaches while consuming a small fraction of the power. The new processor is fast enough to plan and operate in real time, and power-efficient enough to be used in large-scale manufacturing environments with thousands of robots.
DNA may be the blueprint of life, but it’s also a molecule made from just a few simple chemical building blocks. Among its properties is the ability to conduct an electrical charge, fueling an engineering race to develop novel, low-cost nanoelectronic devices.
Now, a team led by ASU Biodesign Institute researcher Nongjian “N.J.” Tao and Duke theorist David Beratan has been able to understand and manipulate DNA to more finely tune the flow of electricity through it. The key findings, which can make DNA behave in different ways — cajoling electrons to smoothly flow like electricity through a metal wire, or hopping electrons about like the semiconductors materials that power our computers and cellphones — pave the way for an exciting new avenue of research advancements.
The results, published in the online edition of Nature Chemistry, may provide a framework for engineering more stable and efficient DNA nanowires, and for understanding how DNA conductivity might be used to identify gene damage.
Building on a series of recent works, the team has been able to better understand the physical forces behind DNA’s affinity for electrons.
“We’ve been able to show theoretically and experimentally that we can make DNA tunable by changing the sequence of the ‘A, T, C, or G’ chemical bases, by varying its length, by stacking them in different ways and directions, or by bathing it in different watery environments,” said Tao, who directs the Biodesign Center for Biolectronics and Biosensors and is a professor in the Ira A. Fulton Schools of Engineering.
Man-made blood vessels developed by researchers at Duke University, Yale University and the tissue engineering company Humacyte appear to be both safe and more durable than commonly used synthetic versions in patients undergoing kidney dialysis, the researchers report.
The findings, published May 12 in The Lancet, resulted from a phase 2 study among 60 patients with kidney failure who required dialysis, which often requires a synthetic graft when the patient’s own blood vessel degrades from frequent needle sticks.
Such grafts, however, are prone to infection, clotting, and other complications. And alternative bioengineered grafts derived from the patient, a donor, or animal tissue have been shown to perform no better than synthetics.
The Duke and Yale research team — along with surgeons in Poland and the United States and scientists at Humacyte, which is developing the bioengineered vessel — tested a human acellular vessel, or HAV, that is manufactured to be available to patients on demand, rather than made-to-order using an individual’s own cells.
“The bioengineered blood vessel represents a critical step in tissue engineering,” said Jeffrey Lawson, M.D., Ph.D., professor of surgery and pathology at Duke and chief medical officer of Humacyte. “Because these vessels contain no living cells, patients have access to off-the-shelf engineered grafts that can be used without any waiting period associated with tailor-made products.”
Lawson and co-author Laura Niklason, M.D., Ph.D., professor of anesthesiology and biomedical engineering at Yale, are principals of Humacyte, Inc., which supported the clinical trial.
To create the vessels, the researchers first isolated vascular cells from human donors and grew them in tissue culture. They then placed the cells on a degradable scaffold shaped like a blood vessel. As the tissue grew, it was bathed in nutrients and stretched to acquire the physical properties of real blood vessels.
“After that process, which takes eight weeks, the scaffold degrades and what we have left is engineered tissue that we have grown from scratch,” Niklason said.
The final step was to wash away the cells with a special solution. The remaining “de-cellularized” tissue retains the structure of the vessel but none of the components that would cause tissue rejection.
One year after implantation, the bioengineered vessels appeared to be both safe and functional, maintaining their mechanical integrity, the researchers report. The patients also showed no sign of rejection.
While there were cases of adverse events such as clotting, the rates of those events were comparable to other dialysis grafts. Notably, the durability of the bioengineered vessels at one year was 89 percent, compared to the approximately 60-percent rate of synthetic grafts reported in previous studies.
Additionally, the researchers noted that after implantation, the bioengineered vessels had been repopulated with the patient’s own cells, so nonliving tissue became living over time.
“The fact that an implanted acellular tube becomes a living human tissue has implications for regenerative medicine in a very profound way,” Lawson said.
Limb or organ regrowth may be hidden in our genes
If you trace our evolutionary tree way back to its roots — long before the shedding of gills or the development of opposable thumbs — you will likely find a common ancestor with the amazing ability to regenerate lost body parts. In an effort to understand what was lost, researchers have built a running list of the genes that enable regenerating animals to grow back a severed tail or repair damaged tissues.
A Duke study appearing April 6 in the journal Nature has discovered the presence of these regulatory sequences in zebrafish, a favored model of regeneration research. Called “tissue regeneration enhancer elements” or TREEs, these sequences can turn on genes in injury sites and even be engineered to change the ability of animals to regenerate.
New technique speeds tissue engineering of functional arteries
Duke engineers have developed a technique to make artificial arteries that naturally produce biochemical signals vital to their functions. The technique is also ten times faster than current methods for tissue engineering of blood vessels.
Arterial walls have multiple layers of cells, including the endothelium and media. The endothelium is the innermost lining of all blood vessels that interacts with circulating blood. The media is made mostly of smooth muscle cells that help control the flow and pressure of the blood within. These two layers communicate through a suite of chemical signals that control how the vascular system reacts to stimuli such as drugs and exercise.
In a new study, biomedical engineers from Duke’s Pratt School of Engineering successfully engineered artificial arteries containing both layers and demonstrated their ability to communicate and function normally.
The blood vessels being reported Feb. 18 in Nature Scientific Reports are also miniaturized to enable 3D microscale artificial organ platforms to test drugs for efficacy and side effects. The new technique may also enable researchers to conduct experiments on arterial replacements in record time.
“We wanted to focus on arteries because that’s where most of the damage is caused in coronary diseases,” said George Truskey, the R. Eugene and Susie E. Goodson Professor of Biomedical Engineering and Vinik Dean of the Pratt School of Engineering at Duke.
“Most previous studies had focused on the media cells but hadn’t spent much time on the endothelial cells, and nobody had shown how the two would interact,” Truskey said. “Many of the techniques for creating artificial tissue also were rather lengthy, which was frustrating.”
The frustration came from the six-to-eight weeks it took to grow arteries in the laboratory. Turning to the literature, Truskey found a paper detailing a much faster technique used to create a trachea. The method works by putting cells of the desired tissue inside collagen and compressing for a few minutes. This both squeezes out excess water and increases the mechanical strength of the resulting tissue.
For the next six months, graduate student Cristina Fernandez worked to convert the technique so she could create arteries. And not just any arteries — arteries scaled down to one tenth the size of a typical human’s, which made the translation even trickier.
“With a smaller diameter, we could make a lot of these artificial vessels in a short amount of time,” said Truskey. “We can make these vessels and use them in only a few hours. To me that was the biggest advance, because spending several weeks on each set was driving me crazy.”
Once that hurdle was passed, the team tested the new arteries to see how they would respond to natural and artificial stimuli. In one test, they administered statins to see if they would block inflammation as they do in patients. In another test, the researchers looked to see if chemical signals released from the endothelial cells would cause the media layer to relax and constrict, as they do in the human body.
In both instances, the engineered arteries behaved normally.
The next step, according to Truskey, is to look at how some select rare genetic diseases affect the arteries. The end goal is to create a system that can be used to test drugs that is more accurate and reliable than animal models.
That goal is part of the Tissue Chip for Drug Screening program, which is funded by the National Institutes of Health to improve ways of predicting drug safety and effectiveness. The program is tasked with creating 3-D human tissue chips and combining them into an integrated system that mimics the complex functions of the human body, so that promising pharmaceuticals can be better tested before entering human trials.
At Duke, one side of the project has already demonstrated the fabrication of skeletal muscle that responds physiologically to stimuli such as drugs. With the development of these small artificial arteries, the two systems can be connected and eventually integrated with other tissue proxies, such as artificial, functioning liver tissue, which is also being pursued at Duke.
But the new technique also could be a boon to researchers everywhere creating artificial arteries.
“While our arteries are small and intended for testing, they’re just as mechanically strong as those intended to be put inside of the body,” said Truskey. “So the technique could be beneficial to researchers trying to create artificial arteries to replace damaged ones in patients as well.”